This invention relates to an improved roll for use with machinery for processing flat rolled products wherein objectionable load created deflections are self-compensated.
In the rolling of flat rolled strip-like products, such as hot and cold carbon steel strip, rubber, plastics, paper and the like the rolls that are employed to process the material deflect between their oppositely held ends when the center portion of the roll is engaged by the material. This deflection results in unacceptable product conditions due to its affect on the uniformity of the cross section i.e., profile and flatness of the strip and edge reduction (edge drop) and the inability to satisfactorily correct these conditions.
In the past, and particularly in the rolling mill industry to which for purposes of explaining the invention reference will hereinafter be made, attempts have been made to eliminate some or all of these adverse conditions during the rolling process. These attempts included roll bending in combination with a predetermined machine roll crown, employment of special shaped work rolls and/or back up rolls including fluid expandable rolls, shiftable rolls and thermal roll crown control, etc.
To better appreciate the present invention and also to serve as background information for a better understanding thereof two particular prior art forms will be more fully referred to. First, is the disclosure of U.S. Pat. No. 4,299,109 where there is shown a sleeve shifting device having a solid arbor and loose outer sleeve of the backing up roll construction, the sleeve being shiftable to attempt to reduce deflection of the portion of the work rolls extending beyond the edges of the strip being rolled. The second prior art form has reference to U.S. Pat. No. 4,407,151 which illustrates a internal shifting arbor of a backing up roll construction which attempts to accomplish the same result as the first noted prior art arrangement. In the present invention the arbor and sleeve, in the form of a two piece construction, is rigidly secured to each other to achieve the same objectives of the two prior art forms by the appropriate configuration of the sleeve geometry designed to cover a wide range of width strips.
However, none of these attempts have been totally successful, particularly due to the fact of the many variables involved in a normal rolling operation, such as the change on the width of the strips being rolled and degree of reduction from one strip to another, the change in temperature of succeeding strips, and the change in temperature of the strip while being rolled and that of the mill itself.
Another aspect of one of the conditions that gives rise to an unacceptable product, and which represents a principle part thereof, is the constant change that takes place in the shape or contour of the rolling surface of the work rolls of the mill when subject to the constant change in temperature and loading. Even in the case where it is desirable to produce a product with a degree of non-uniform profile, it has been extremely difficult in the past to obtain the required stability of rolling conditions and particularly the shape or contour of the rolling surfaces of the work rolls to obtain the desired profile throughout the strip and from strip to strip.
Also in the past for essentially the same reasons it has been extremely difficult to obtain flat strip i.e. free of buckles and waves and prevent over reduction of the edges by employment of the above-mentioned corrective means and procedures.
The present invention provides at least a substantial solution to these problems in providing a roll which by its very nature will greatly reduce, if not eliminate, roll deflection in the context discussed above thereby creating a flat or if desired, a controlled degree of flatness or profile of a contacting surface of the roll which could be a rolling surface or in the case of a multi high roll arrangement a surface that engages a second roll.
Another aspect of the present invention is to provide a rolling surface that will substantially remain unchanged during the rolling procedure and as a result greatly reduce the degree of external changes that will have to be performed, if any, in order to obtain a flat rolling surface or a controlled contour rolling surface.
A still further object of the present invention is to provide a controlled rolling surface in terms of its contour which in combination with known external means, such as roll bending, will compensate for the adverse affect of roll deflection over rolling conditions having a wide range of variables such as a change in the width or type of strip, amount of reduction, temperature variation, etc.